Laws Of Motion

The masses of block \(A\) and \(B\) are \(m\) and \(M\), respectively. Between \(A\) and \(B\), there is a constant frictional force \(F\) and \(B\) can slide on a smooth horizontal surface. A is set in motion with velocity \(3 v_0\) while \(B\) is at rest. What is the distance moved by \(A\) relative to \(B\) before they move with the same velocity?